U.S. patent number 9,765,623 [Application Number 13/948,240] was granted by the patent office on 2017-09-19 for methods for modifying cooling holes with recess-shaped modifications.
This patent grant is currently assigned to General Electric Company. The grantee listed for this patent is General Electric Company. Invention is credited to Yan Cui, Srikanth Chandrudu Kottilingam, Gareth William David Lewis, Jonathan Matthew Lomas, David Edward Schick, Brian Lee Tollison.
United States Patent |
9,765,623 |
Kottilingam , et
al. |
September 19, 2017 |
Methods for modifying cooling holes with recess-shaped
modifications
Abstract
A Method for modifying a plurality of cooling holes of a turbine
component includes disposing a recess-shaped modification in a
recess of the component comprising a plurality of cooling hole
outlets, wherein the recess-shaped modification is formed to
substantially fill the recess and comprising a plurality of
modified cooling holes passing there through. The method further
includes aligning the plurality of modified cooling holes of the
recess-shaped modification with the plurality of cooling hole
outlets of the component, inserting at least one alignment pin into
at least one of aligned pair of holes and hole outlets, bonding the
recess-shaped modification disposed in the recess to the component,
and removing the at least one alignment pin after bonding, wherein
the plurality of modified cooling holes of the recess-shaped
modification is fluidly connected with the plurality of cooling
holes of the component.
Inventors: |
Kottilingam; Srikanth Chandrudu
(Simpsonville, SC), Cui; Yan (Greer, SC), Tollison; Brian
Lee (Honea Path, SC), Schick; David Edward (Greenville,
SC), Lomas; Jonathan Matthew (Simpsonville, SC), Lewis;
Gareth William David (Greenville, SC) |
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Assignee: |
General Electric Company
(Schenectady, NY)
|
Family
ID: |
51205287 |
Appl.
No.: |
13/948,240 |
Filed: |
July 23, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20150030460 A1 |
Jan 29, 2015 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23P
6/005 (20130101); F01D 5/186 (20130101); F01D
5/005 (20130101); F01D 5/182 (20130101); F01D
5/187 (20130101); F01D 5/20 (20130101); F05D
2230/80 (20130101); F05D 2230/22 (20130101); F05D
2230/236 (20130101); B23P 2700/06 (20130101); Y10T
29/49737 (20150115); F05D 2240/307 (20130101); Y10T
29/49318 (20150115); Y02T 50/676 (20130101); Y10T
29/49902 (20150115); Y02T 50/60 (20130101); Y02T
50/671 (20130101) |
Current International
Class: |
F01D
5/00 (20060101); B23P 6/00 (20060101); F01D
5/18 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1245691 |
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Oct 2002 |
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EP |
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1245691 |
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Nov 2002 |
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EP |
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2230381 |
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Sep 2010 |
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EP |
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2540971 |
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Jan 2013 |
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EP |
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2009041449 |
|
Feb 2009 |
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JP |
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03048528 |
|
Jun 2003 |
|
WO |
|
Other References
English Machine Translation of JP3957214(B2) published Aug. 15,
2007 (also published as WO03048528A1). cited by examiner .
European Search Report and Opinion issued in connection with
corresponding EP Application No. 14177404.2 on Feb. 10, 2015. cited
by applicant.
|
Primary Examiner: Afzali; Sarang
Attorney, Agent or Firm: Cusick; Ernest G. Landgraff; Frank
A.
Claims
What is claimed is:
1. A method for modifying a plurality of cooling holes of a turbine
component, the method comprising: disposing a recess-shaped
modification in a recess of the component comprising a plurality of
cooling hole outlets, the recess-shaped modification formed to
substantially fill the recess and comprising a plurality of
modified cooling holes passing there through; aligning each cooling
hole of the plurality of modified cooling holes of the
recess-shaped modification with a corresponding cooling hole outlet
of the plurality of cooling hole outlets of the component;
inserting at least one alignment pin into at least one of aligned
pair of the plurality of modified cooling holes of the
recess-shaped modification and the plurality of cooling hole
outlets of the component; bonding the recess-shaped modification
disposed in the recess to the component; and removing the at least
one alignment pin from the at least one of aligned pair of the
plurality of modified cooling holes of the recess-shaped
modification and the plurality of cooling hole outlets of the
component after bonding to fluidly connect the plurality of
modified cooling holes of the recess-shaped modification aligned
with the plurality of cooling hole outlets of the component.
2. The method of claim 1, wherein the turbine component comprises a
turbine bucket and the plurality of cooling hole outlets are
disposed at a bucket tip.
3. The method of claim 2, wherein the recess filled by the
recess-shaped modification is adjacent a trailing edge of the
turbine bucket.
4. The method of claim 1, wherein the recess-shaped modification
comprises a pre-sintered preform, wherein the pre-sintered preform
comprises a mixture comprising a base alloy and a second alloy, the
base alloy comprising about 30 weight percent to about 90 weight
percent of the mixture and the second alloy comprising a sufficient
amount of a melting point depressant to have a lower melting
temperature than the base alloy.
5. The method of claim 4, wherein the pre-sintered preform is
formed by combining base alloy particles and second alloy particles
with a binder to form a combined powder mixture, compacting the
combined powder mixture to form a compacted preform, and heating
the compacted preform to remove the binder and form the
pre-sintered preform.
6. The method of claim 1 further comprising removing an outer
portion of the component to form the recess prior to disposing the
recess-shaped modification therein.
Description
BACKGROUND OF THE INVENTION
The subject matter disclosed herein relates to cooling holes and,
more specifically, to modifying cooling holes for turbine
components.
In gas turbine engines, such as aircraft engines or heavy duty gas
turbines for example, air is drawn into the front of the engine,
compressed by a shaft-mounted rotary-type compressor, and mixed
with fuel. The mixture is burned, and the hot exhaust gases are
passed through a turbine mounted on a shaft. The flow of gas turns
the turbine, which turns the shaft and drives the compressor and
fan. The hot exhaust gases flow from the back of the engine,
driving it and the aircraft forward.
During operation of gas turbine engines, the temperatures of
combustion gases may exceed 3,000.degree. F., considerably higher
than the melting temperatures of the metal parts of the engine
which are in contact with these gases. Operation of these engines
at gas temperatures that are above the metal part melting
temperatures is a well-established art, and depends in part on
supplying a cooling air to the outer surfaces of the metal parts
through various methods. The metal parts of these engines that are
particularly subject to high temperatures, and thus require
particular attention with respect to cooling, are the metal parts
forming combustors and parts located aft of the combustor, in the
so-called "hot gas path". For example, the operating temperatures
can be partially regulated by using passageways such as cooling
holes incorporated into some engine components such as buckets.
Superalloys, such as precipitation-hardenable Ni-based superalloys,
or Co-based superalloys, can be used for turbine components to help
withstand higher operating temperatures. However, the modification
of these materials, particularly around cooling holes (e.g.,
proximate the tip of a bucket), may also require significant
resources such as for properly preheating and/or cooling weld
repair sites, removing original material, building up new material,
and finishing any final surfaces into compliance ranges. As a
result, modifying cooling holes through welding/brazing can require
additional resources and time to allow for sufficient joining of
additional material.
Accordingly, alternative methods for modifying cooling holes would
be welcome in the art.
BRIEF DESCRIPTION OF THE INVENTION
In one embodiment, a method is disclosed for modifying a plurality
of cooling holes of a component. The method includes disposing a
recess-shaped modification in a recess of the component comprising
a plurality of cooling hole outlets, the recess-shaped modification
formed to substantially fill the recess and comprising a plurality
of modified cooling holes passing there through. The method further
includes aligning the plurality of modified cooling holes of the
recess-shaped modification with the plurality of cooling hole
outlets of the component, and, bonding the recess-shaped
modification disposed in the recess to the component, wherein the
plurality of modified cooling holes of the recess-shaped
modification is fluidly connected with the plurality of cooling
holes of the component.
In another embodiment, another method for modifying a plurality of
cooling holes of a component is disclosed. The method includes
disposing a recess-shaped modification in a recess of the component
comprising a plurality of cooling hole outlets, the recess-shaped
modification formed to substantially fill the recess. The method
further includes forming a plurality of modified cooling holes
through the recess-shaped modification that align with the
plurality of cooling hole outlets of the component, and, bonding
the recess-shaped modification in the recess to the component,
wherein the plurality of modified cooling holes of the
recess-shaped modification is fluidly connected with the plurality
of cooling holes of the component.
In yet another embodiment, a modified component in disclosed. The
modified component includes an original component base comprising a
plurality of cooling holes therein, the plurality of cooling holes
having a plurality of cooling hole outlets at a recess. The
modified component further includes a recess-shaped modification
disposed in the recess and comprising a plurality of modified
cooling holes that align with the plurality of cooling hole outlets
of the original component base, and wherein, the recess-shaped
modification is bonded to the original component base such that the
plurality of modified cooling holes of the recess-shaped
modification is fluidly connected with the plurality of cooling
holes of the original component base.
These and additional features provided by the embodiments discussed
herein will be more fully understood in view of the following
detailed description, in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The embodiments set forth in the drawings are illustrative and
exemplary in nature and not intended to limit the inventions
defined by the claims. The following detailed description of the
illustrative embodiments can be understood when read in conjunction
with the following drawings, where like structure is indicated with
like reference numerals and in which:
FIG. 1 is a perspective view of a component having a recess
according to one or more embodiments shown or described herein;
FIG. 2 is an exploded view of a recess-shaped modification filling
a recess of a component according to one or more embodiments shown
or described herein;
FIG. 3 is a method of modifying a plurality of cooling holes of a
component according to one or more embodiments shown or described
herein; and,
FIG. 4 is another method of modifying a plurality of cooling holes
of a component according to one or more embodiments shown or
described herein.
DETAILED DESCRIPTION OF THE INVENTION
One or more specific embodiments of the present invention will be
described below. In an effort to provide a concise description of
these embodiments, all features of an actual implementation may not
be described in the specification. It should be appreciated that in
the development of any such actual implementation, as in any
engineering or design project, numerous implementation-specific
decisions must be made to achieve the developers' specific goals,
such as compliance with system-related and business-related
constraints, which may vary from one implementation to another.
Moreover, it should be appreciated that such a development effort
might be complex and time consuming, but would nevertheless be a
routine undertaking of design, fabrication, and manufacture for
those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present
invention, the articles "a," "an," "the," and "said" are intended
to mean that there are one or more of the elements. The terms
"comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements.
The present disclosure is generally applicable to components that
operate within environments characterized by relatively high
temperatures, and particularly a component whose maximum surface
temperature approaches the melting temperature of the material from
which it is formed, necessitating the use of forced air cooling to
reduce the component surface temperature. Notable examples of such
components include the high and low pressure turbine buckets
(blades), nozzles (vanes), shrouds, and other hot gas path
components of a turbine, such as an industrial or aircraft gas
turbine engine.
Referring now to FIGS. 1 and 2, an exemplary modified component 10
is illustrated comprising a turbine bucket. The modified component
10 generally includes an airfoil 12 against which hot combustion
gases are directed during operation of the gas turbine engine, and
whose surface is therefore subjected to very high temperatures. The
airfoil 12 is represented as configured to be anchored to a turbine
disk (not shown) with a dovetail 14 formed on a root section of the
modified component 10 that is separated from the airfoil 12 by a
platform 16. The airfoil 12 includes internal cooling passages 18
(e.g., cooling holes) through which bleed air that enters the
modified component 10 through its root section is forced to
transfer heat from the modified component 10. As will become
appreciated herein, the modified component 10 further comprises a
recess-shaped modification 30 that fills a previously formed recess
to modify the cooling holes 18. This recess-shaped modification 30
may allow for distress and/or oxidation at the cooling holes 18 to
be removed by forming the recess, while subsequently reforming the
lost portion of the cooling holes 18 via the modified cooling holes
38 (i.e. new/replacement cooling hole portions) of the
recess-shaped modification 30. Such embodiments can avoid having to
build up via welding and/or brazing. While the advantages of this
invention will be described with reference to the modified
component 10 shown as a bucket in FIG. 1, the teachings of this
invention are generally applicable to other hot gas path components
of industrial and aircraft gas turbine engines, as well as a
variety of other components that are subjected to extreme
temperatures.
Referring now to FIG. 2, an exploded view of a modified component
10 is illustrated comprising an original component base 11 (also
referred to simply as the "component") and a recess-shaped
modification 30. As used herein, "original component base" refers
to the bulk of the original component that is modified through the
addition of the recess-shaped modification 30. "Original" only
refers to relative state of the component prior to the modification
discussed herein, and not necessarily a new-make component. For
example, the "original component base" can refer to a turbine
bucket that underwent several hours of operation and is now in need
of modification (e.g., repair or maintenance).
The original component base 11 generally comprises a plurality of
cooling holes 18 (i.e., an internal passage that facilitates the
flow of a fluid medium such as air) that have cooling hole outlets
28. The cooling hole outlets 28 can be disposed at an outer surface
22 of the original component base 11. Specifically, the base
component can have a recess 20 formed by removing an outer portion
of the original component base 11 such that at least some of the
cooling hole outlets 28 on the outer surface 22 are disposed within
the recess 20. The recess 20 can comprise any suitable depth, width
and other dimensions with respect to the original geometry of the
original component base 11. For example, the cooling hole outlet 28
exposed by the removal of material when forming the recess 20, can
comprise any previously internal portion of the internal cooling
passageways including the portions more proximate the surface, or
the more internal portions utilized to distribute cooling air. Such
recesses can also be formed anywhere about the outer surface that
can comprise one or more cooling hole outlets. For example, when
the component comprises a turbine bucket, the plurality of cooling
hole outlets 28 disposed in the recess 20 may be present at the
bucket tip. In even some specific embodiments, the recess 20 may be
formed adjacent the trailing edge 13 of the turbine bucket such
that the recess-shaped modification 30 replaces a portion of the
turbine bucket about its trailing edge 13. By removing the outer
portion from the original component base 11 to form the recess 20,
areas of oxidation, cracks and/or other forms of distress (such as
those potentially originating around one or more cooling holes 18)
may be removed.
The cooling holes 18 and the cooling hole outlets 28 can be
disposed at any relative locations and comprise any configuration
that assists in cooling the original component base 11 when in
operation. For example, in some embodiments, the cooling holes 18
may comprise a serpentine configuration internal the original
component base 11. In some embodiments, multiple cooling holes 18
may be interconnected.
The original component base 11 can comprise a variety of materials
such as one or more superalloys. In some embodiments, the base
article can comprise a nickel-, cobalt-, or iron-based superalloy.
For example, the original component base 11 can comprise
nickel-based superalloys such as Rene N4, Rene N5, Rene 108,
GTD-111.RTM., GTD-222.RTM., GTD-444.RTM., IN-738 and MarM 247 or
cobalt-based superalloys such as FSX-414. The base component may be
formed as an equiaxed, directionally solidified (DS), or single
crystal (SX) casting to withstand the high temperatures and
stresses to which it is subjected such as within a gas turbine
engine.
Referring to FIGS. 1 and 2, the modified component 10 further
comprises the recess-shaped modification 30. The recess-shaped
modification 30 is shaped to substantially fill the recess 20
formed in the original component base 11 (i.e., the component). As
used herein, "substantially fill" refers to the size, shape and
overall profile of the recess-shaped modification 30 being
substantially matched to the size, shape and profile of the recess
20. Thus, where the recess negatively removed an outer portion of
material from the base component, the recess-shaped modification 30
positively provides material as a replacement so that the outer
profile of the modified component 10 is substantially similar to
the outer profile of the original component base 11 prior to the
creation of the recess 20.
The recess-shaped modification 30 further comprises a plurality of
modified cooling holes 38. The plurality of cooling holes pass from
an interior surface 31 (the surface adjacent the original component
base 11 once installed) to an exterior surface 32 (the surface that
forms part of the exterior of the modified component 10). Similar
to the cooling holes 18 of the original component base 11, the
modified cooling holes 38 are internal passages that facilitate the
flow of a fluid medium such as air. In some embodiments, the
modified cooling holes 38 can have the same diameter, cross section
and/or other dimensions as the cooling holes 18 of the base
component. In other embodiments, one or more of said dimensions may
vary such that a fluid may flow there between once fluidly
connected as will become appreciated herein. These modified cooling
holes 38 can thereby replace the portion of the cooling holes 18 of
the original component base 11 that were removed when forming the
recess 20. As such, any areas of oxidation, cracks and/or other
forms of distress (such as those potentially originating around one
or more cooling holes 18) may be replaced by the modified cooling
holes 38 free of such distress.
The modified cooling holes 38 may be present in the recess-shaped
modification 30 prior to disposing it in the recess 20, may be
formed in the recess-shaped modification 30 once it is already
disposed in the recess 20, or combinations thereof. For example, in
some embodiments modified cooling holes 38 are formed in the
manufacturing of the recess-shaped modification 30. In some
embodiments, modified cooling holes 38 are machined (e.g., drilled)
into the recess-shaped modification 30 post creation of the
recess-shaped modification 30 but prior to disposing it in the
recess 20. In even some embodiments, modified cooling holes 38 are
machined (e.g., drilled) into the recess-shaped modification 30 is
already disposed in the recess 20.
The recess-shaped modification 30 can comprise a variety of
materials. For example, in some embodiments, the recess-shaped
modification 30 can comprise a nickel-, cobalt-, or iron-based
superalloy such as those discussed above. In even some of these
embodiments, such as when the original component base 11 comprises
a turbine bucket or other turbine component, the recess-shaped
modification 30 and the original component base 11 may share a
common composition (i.e., they are the same type of material).
In some embodiments, the recess-shaped modification 30 may comprise
a pre-sintered preform. The pre-sintered preform comprises a
mixture of particles comprising a base alloy and a second alloy
that have been sintered together at a temperature below their
melting points to form an agglomerate and somewhat porous mass.
Suitable particle size ranges for the powder particles include 150
mesh, or even 325 mesh or smaller to promote rapid sintering of the
particles and minimize porosity in the pre-sintered preform 30 to
about 10 volume percent or less. In some embodiments, the density
of the pre-sintered preform 30 has a density of 90% or better. In
even some embodiments, the pre-sintered preform 30 has a density of
95% or better.
The base alloy of the pre-sintered preform can comprise any
composition such as one similar to the original component base 11
to promote common physical properties between the pre-sintered
preform recess-shaped modification 30 and the base component 20.
For example, in some embodiments, the base alloy (of the
pre-sintered preform) and the original component base 11 share a
common composition (i.e., they are the same type of material). In
some embodiments, the base alloy can comprise nickel-based
superalloys such as Rene N4, Rene N5, Rene 108, GTD-111.RTM.,
GTD-222.RTM., GTD-444.RTM., IN-738 and MarM 247 or cobalt-based
superalloys such as FSX-414 as discussed above. In some
embodiments, the properties for the base alloy include chemical and
metallurgical compatibility with the original component base 11,
such as high fatigue strength, low tendency for cracking, oxidation
resistance and/or machinability.
In some embodiments, the base alloy may comprise a melting point of
within about 25.degree. C. of the melting temperature of the
original component base 11. In some embodiments, the base alloy may
comprise a compositional range of, by weight, about 2.5 to 11%
cobalt, 7 to 9% chromium, 3.5 to 11% tungsten, 4.5 to 8% aluminum,
2.5 to 6% tantalum, 0.02 to 1.2% titanium, 0.1 to 1.8% hafnium, 0.1
to 0.8% molybdenum, 0.01 to 0.17% carbon, up to 0.08% zirconium, up
to 0.60 silicon, up to 2.0 rhenium, the balance being nickel and
incidental impurities. In even some embodiments, the base alloy may
comprise a compositional range of, by weight, about 9 to 11%
cobalt, 8 to 8.8% chromium, 9.5 to 10.5% tungsten, 5.3 to 5.7%
aluminum, 2.8 to 2.3% tantalum, 0.9 to 1.2% titanium, 1.2 to 1.6%
hafnium, 0.5 to 0.8% molybdenum, 0.13 to 0.17% carbon, 0.03 to
0.08% zirconium, the balance nickel and incidental impurities. It
should be appreciated that while specific materials and
compositions have been listed herein for the composition of the
base alloy of the pre-sintered preform recess-shaped modification
30, these listed materials and compositions are exemplary only and
non-limiting and other alloys may alternatively or additionally be
used. Furthermore, it should be appreciated that the particular
composition of the base alloy for the pre-sintered preform may
depend on the composition of the original component base 11.
As discussed above, the pre-sintered preform further comprises a
second alloy. The second alloy may also have a composition similar
to the original component base 11 but further contain a melting
point depressant to promote sintering of the base alloy and the
second alloy particles and enable bonding of the pre-sintered
preform recess-shaped modification 30 to the original component
base 11 at temperatures below the melting point of the original
component base 11. For example, in some embodiments the melting
point depressant can comprise boron and/or silicon.
In some embodiments, the second alloy may comprise a melting point
of about 25.degree. C. to about 50.degree. C. below the grain
growth or incipient melting temperature of the original component
base 11. Such embodiments may better preserve the desired
microstructure of the original component base 11 during the heating
process. In some embodiments, the second alloy may comprise a
compositional range of, by weight, about 9 to 10% cobalt, 11 to 16%
chromium, 3 to 4% aluminum, 2.25 to 2.75% tantalum, 1.5 to 3.0%
boron, up to 5% silicon, up to 1.0% yttrium, the balance nickel and
incidental impurities. For example, in some embodiments the second
alloy may comprise commercially available Amdry DF4B nickel brazing
alloy. It should also be appreciated that while specific materials
and compositions have been listed herein for the composition of the
second alloy of the pre-sintered preform recess-shaped modification
30, these listed materials and compositions are exemplary only and
non-limiting and other alloys may alternatively or additionally be
used. Furthermore, it should be appreciated that the particular
composition of the second alloy for the pre-sintered preform
recess-shaped modification 30 may depend on the composition of the
original component base 11.
The pre-sintered preform can comprise any relative amounts of the
base alloy and the second alloy that are sufficient to provide
enough melting point depressant to ensure wetting and bonding
(e.g., diffusion/brazing bonding) of the particles of the base
alloy and the second alloy to each other and to the outer surface
22 of the original component base 11. For example, in some
embodiments the second alloy can comprise at least about 10 weight
percent of the pre-sintered preform. In some embodiments the second
alloy can comprise no more than 70 weight percent of the
pre-sintered preform. Such embodiments may provide a sufficient
amount of melting point depressant while limiting potential
reduction of the mechanical and environmental properties of the
subsequent heating. Furthermore, in these embodiments, the base
alloy can comprise the remainder of the pre-sintered preform (e.g.,
between about 30 weight percent and about 70 weight percent of the
pre-sintered preform). In even some embodiments, the particles of
the base alloy can comprise about 40 weight percent to about 70
weight percent of the pre-sintered preform with the balance of the
composition comprising particles of the second alloy. It should be
appreciated that while specific relative ranges of the base alloy
and the second alloy have been presented herein, these ranges are
exemplary only and non-limiting and any other relative compositions
may also be realized such that a sufficient amount of melting point
depressant is provided as discussed above.
Aside from the particles of the base alloy and the second alloy, no
other constituents are required within the pre-sintered preform.
However, in some embodiments, a binder may be initially blended
with the particles of the base alloy and the second alloy to form a
cohesive mass that can be more readily shaped prior to sintering.
In such embodiments, the binder can include, for example, a binder
commercially available under the name NICROBRAZ-S from the Wall
Colmonoy Corporation. Other potentially suitable binders include
NICROBRAZ 320, VITTA GEL from Vitta Corporation, and others
including adhesives commercially available from Cotronics
Corporation, all of which may volatilize cleanly during
sintering.
The pre-sintered preform may be formed by mixing the powder
particles of the base alloy (i.e., base alloy particles) and the
second alloy (i.e., second alloy particles) by any suitable means
such as stirring, shaking, rotating, folding or the like or
combinations thereof. After mixing, the mixture may be combined
with the binder (i.e., to form a combined powder mixture) and cast
into shapes (i.e., to form a compacted preform), during and/or
after which the binder can be burned off. The compacted preform may
then be placed in a non-oxidizing (vacuum or inert gas) atmosphere
furnace for the sintering operation, during which the powder
particles of the base alloy and the second alloy undergo sintering
to yield the pre-sintered preform with good structural strength and
low porosity. Suitable sintering temperatures may at least in part
depend on the particular compositions of the particles of the base
alloy and the second alloy. For example, in some embodiments, the
sintering temperature may be in a range of about 1010.degree. C. to
about 1280.degree. C. In some embodiments, following sintering, the
pre-sintered preform can be HIPed or vacuum pressed to achieve
densities greater than 95%.
In some embodiments the modified component 10 may have at least one
additional coating on an exterior surface 32 of the recess-shaped
modification 30. The coating can comprise any type of coating that
may be suitable for the modified component 10 when in operation
such as those that assist in thermal, mechanical, or other
performance. For example, in some embodiments, such as when the
modified component 10 comprises a hot gas path component for a
turbine, the coating can comprise a thermal barrier coating and/or
an environmental barrier coating. Exemplary, but non-limiting
coatings include one or more bond coats, transition or intermediate
layers, and/or topcoats. Non-limiting materials for the coatings
include ceramic materials, a notable example of which is zirconia
partially or fully stabilized with yttria (YSZ) or another oxide
such as magnesia, ceria, scandia and/or calcia, and optionally
other oxides to reduce thermal conductivity. Bond coat materials
used in thermal barrier coating systems include oxidation-resistant
overlay coatings such as MCrAlX (where M is iron, cobalt and/or
nickel, and X is yttrium, a rare-earth metal, and/or another
reactive metal), and oxidation-resistant diffusion coatings.
The coating can be deposited to a thickness that is sufficient to
provide a desired level of thermal protection for the underlying
surface region such as, for example, on the order of about 75 to
about 300 micrometers, though lesser and greater thicknesses are
also possible. The coating 40 can be applied to the recess-shaped
modification 30 (e.g., pre-sintered preform) prior to bonding the
recess-shaped modification 30 to the base article 20, after bonding
the recess-shaped modification 30 to the base article 20, or
combinations thereof.
Referring to FIG. 2, the interior surface 31 of the recess-shaped
modification 30 is disposed on the outer surface 22 of the recess
20 of the original component base 11 such that the plurality of
modified cooling holes 38 of the recess-shaped modification 30 are
aligned with the cooling hole outlets 28 of the original component
base 11. Alignment may be achieved in a variety of methods
depending in part on whether the plurality of modified cooling
holes 38 were present in the recess-shaped modification 30 prior to
or post disposing it in the recess 20.
For example, in embodiments where the recess-shaped modification 30
possesses a plurality of modified cooling holes 38 prior to bonding
it with the modified component 10, one or more alignment pins (not
illustrated) may be temporarily disposed in one of the modified
cooling holes 38 and/or the cooling hole 18 of the component 10 to
aid in alignment of the two pieces. For example, ceramic pins can
be used to temporarily align the recess-shaped modification 30 with
the original component base 11 prior to or during bonding (e.g.,
brazing). Such alignment pins, depending on the material, can be
melted, pulled out, or otherwise removed from the modified
component 10 to leave a fluidly connected cooling hole between the
original component base 11 and the recess-shaped modification
30.
In other embodiments, the plurality of modified cooling holes 38
may be formed (e.g., drilled) into the recess-shaped modification
30 after the recess-shaped modification 30 is already disposed
against or bonded to the original component base 11. In such
embodiments, the modified cooling holes 38 can thereby be aligned
with the cooling hole outlets 28 of the original component base 11
through the formation (e.g., drilling) process.
The recess-shaped modification 30 is bonded to the original
component base 11 by any suitable method giving the materials such
as heating. In some embodiments, such as when the recess-shaped
modification 30 comprises the same alloy as the original component
base 11, this may additional include weld material or the like.
In some embodiments, such as when the recess-shaped modification 30
comprises a pre-sintered preform, heating may occur within a
non-oxidizing (vacuum or inert gas) atmosphere, to a temperature
capable of melting the particles comprising the second alloy (i.e.,
the lower melting particles) of the pre-sintered preform, such as
within a range of about 2050.degree. F. to about 2336.degree. F.
(about 1120.degree. C. to about 1280.degree. C.) (depending on
composition) for a period of about 10 to about 60 minutes. The
second alloy particles can then melt and wet the particles of the
base alloy and the outer surface 22 of the original component base
11 thereby creating a two-phase mixture that alloys together.
Additionally, by using the combination of the base alloy and the
second alloy, the pre-sintered preform may not significantly close
the plurality of cooling holes 18 of the original component base 11
or the plurality of modified cooling holes 38 of the recess-shaped
modification 30.
It should also be appreciated that any type of heating may be
utilized such as, but not limited to, induction heating, torches,
ovens or any other source to sufficiently bond the materials. In
even some embodiments, the heating may be achieved through friction
welding such that the heating process is more localized to the
surface regions.
In some embodiments, a small amount of additional low melt
constituent material can be placed between the recess-shaped
modification 30 and the original component base 11 to increase
brazement quality. Thereafter, the original component base 11 and
the recess-shaped modification 30 can be cooled below the solidus
temperature of the recess-shaped modification 30 to solidify the
mixture and form the superalloy brazement. The brazement can then
undergo a heat treatment at a temperature of about 1975.degree. F.
to about 2100.degree. F. (about 1080.degree. C. to about
1150.degree. C.) the one or more alloys of the recess-shaped
modification with each other and/or the original component base 11.
After heat treatment, any excess material in the brazement can be
removed by grinding or any other suitable method.
In some embodiments, a filler material (not illustrated) may
temporarily be disposed in the cooling holes 18 or modified cooling
holes 18 prior to bonding the recess-shaped modification 30 to the
original component base 11 to ensure the internal the cooling holes
18 and modified cooling holes 38 do not clog. Such filler material
may be disposed through any suitable means and comprise any
suitable material for temporarily stopping-off the passages. For
example, the filler material may comprise a material that does not
melt when the recess-shaped modification 30 is bonded to the
original component base 11, but that can subsequently be removed
via additional heating at a higher temperature, the application of
select chemicals or any other suitable method. Such embodiments may
be particularly suitable for smaller passages such as those with a
diameter of 0.03 inches (0.762 millimeters) or less.
The resulting modified component 10 can thereby comprise a
substantially unitary piece comprising both the original component
base 11 having a recess 20 thereabout and a recess-shaped
modification 30 disposed in and filling said recess 20. The
recess-shaped modification 30 comprises a plurality of modified
cooling holes 38 that align with the cooling hole outlets 28 of the
component such that the a plurality of fluidly connected cooling
holes are formed between the two pieces of the modified component.
Thus, any portion of the original cooling hole previously located
in the now present recess 20 of the base component can be replaced
by the modified cooling hole 38 of the recess-shaped modification
30. This allows for a modular modification (e.g., replacement,
repair or the like) of one or more cooling holes that may have been
in need of modification without the need for extensive braze build
up, welding or other more labor intensive methods.
Referring now to FIG. 3 a method 100 is illustrated for modifying a
plurality of cooling holes of a component. With additional
reference to the exemplary structures illustrated in FIGS. 1 and 2,
the method 100 first comprises disposing a recess-shaped
modification 30 in a recess 20 of the component 10 comprising a
plurality of cooling hole outlets 28 in step 110. As discussed
above, the recess-shaped modification 30 can already comprise a
plurality of modified cooling holes 38 passing there through.
The method 100 further comprises aligning the plurality of modified
cooling holes 38 (of the recess-shaped modification 30) with the
plurality of cooling hole outlets 28 of the component 10 in step
120. In some embodiments, such alignment may be accomplished
through the use of alignment pins as discussed above. Finally, the
method 100 further comprises bonding (e.g., heating) the
recess-shaped modification 30 in the recess 20 to the component 10
in step 130. The resulting bonding allows for fluid connection
between the cooling holes 28 and 38.
Referring now to FIG. 4 another method 101 is illustrated for
modifying a plurality of cooling holes of a component. With
additional reference to the exemplary structures illustrated in
FIGS. 1 and 2, the method 101 first comprises disposing a
recess-shaped modification 30 in a recess 20 of the component 10
comprising a plurality of cooling hole outlets 28 in step 110. As
discussed above, in some embodiments, such as in method 101, the
recess-shaped modification 30 can have the plurality of modified
cooling holes 38 formed after it is disposed in the recess 20. The
plurality of modified cooling holes 38 can thereby be formed (e.g.,
drilled) in step 121 and the recess-shaped modification can be
bonded to the component 10 in step 130. It should be appreciated
that in such embodiments, the hole formation in step 121 and
bonding in step 130 can occur in any relative or simultaneous
order.
While the invention has been described in detail in connection with
only a limited number of embodiments, it should be readily
understood that the invention is not limited to such disclosed
embodiments. Rather, the invention can be modified to incorporate
any number of variations, alterations, substitutions or equivalent
arrangements not heretofore described, but which are commensurate
with the spirit and scope of the invention. Additionally, while
various embodiments of the invention have been described, it is to
be understood that aspects of the invention may include only some
of the described embodiments. Accordingly, the invention is not to
be seen as limited by the foregoing description, but is only
limited by the scope of the appended claims.
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